Mixing panels with different Vmp/Voc

RoySalisburyRoySalisbury Solar Expert Posts: 82 ✭✭✭
I want to add more capacity to my solar setup.  Since I can no longer get the same panels that I currently have, I need to get different panels. However, they are no longer going to have the same specifications.  I'd try to stay with the same overall wattage of the panels, but the Vmp/Voc are not the same.  Currently I have 6 of the following panels:

Kyocera KD320 (320 Watt).  [Vmp - 40.1, Voc - 49.5]

These are setup with 2 in series, and 3 parallel. Going the other way would put me too close to the Voc max rating of the charge controller.

The closest that I can find form "Arizona Win/Sun" is

Silfab Solar 350 (350 watt). [Vmp - 38.9, Voc - 47.5]

When I setup a new string last time they were so far out of spec (210w vs 320w) that I setup a new charge controller just for the 6 320's.  However, that's not an option now.  I'm using an Outback MPPT charge controller (FM60 and FM80).  

My understanding is that if I put 2 more of the 350's in and hooked them in parallel, then I should be fine .. with the restriction that that all my other panels will now get degraded in voltage to the lower set.  Is that right?

If so, then I guess the 'extra' 100 watt on the new panels will make up for the loss.  Also, since the panels normally operate higher then the Vmp, that as long as the newer panels operate above 40.1, then I won't really loose anything.

this is all very confusing.  Any guidance from some experts would be appreciated.

Thanks.

Comments

  • RoySalisburyRoySalisbury Solar Expert Posts: 82 ✭✭✭
    edited January 28 #2
    Just found this thread from 2012 that may be what I'm looking for.  

    http://forum.solar-electric.com/discussion/16660/panels-in-parallel-same-vmp-different-voc

    Seems to indicate that I should be fine as the MPPT will settle on the voltage and the panels will adjust the amp to accommodate.  So really should not lose anything as long as the Vmp of the lower panels does not fall below the Vmp of the higher.  

  • Raj174Raj174 Solar Expert Posts: 519 ✭✭✭✭
    I think it's a good match. The output of the new string should be about the same as the others. Almost as though 320 watt panels were installed.

    Rick
    12 x 300W Renogy PV, MNE175DR-TR epanel modified, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 195AH HI Power LiFePO4 no BMS, 4000W gen.
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